This invention relates to a method for preparing biuret polyisocyanates, and in particular relates to a method for preparing biuret polyisocyanates from hindered diamines and diisocyanates.
It has been known, in the past, to form polyurethanes by reacting polyols and polyisocyanates. Foams may be produced by this reaction if it is conducted in the presence of a blowing agent.
The foams which have been formed in this manner, have in general, been satisfactory but a need for improvement in certain areas still exists. For instance, foams often are shipped in railroad box cars and because of their voluminous nature a great deal of space is needed to transport them. A foam which could be compressed during shipment and decompressed at its destination to its original size and shape would of course be an improvement since it would require less space in transit and enable one to ship greater quantities in the same transporting vehicle.
Further, quality control when preparing polyurethane foams, has been difficult because the ultimate physical properties have been slow to develop after requiring periods up to a few days for completion. Consequently, prompt recognition and rectification of problems could not be made since approximately several days were required on occasion to determine if there was in fact a problem to be solved.
Thus, a need exists for polyurethane foam which may readily be compressed for shipping and also develop ultimate properties rapidly so that quality controls procedures may be applied promptly when they are needed; the foam must not be deficient with respect to any other properties.